Re: [PATCH 2/5] drm/tests: Test drm_rect_calc_hscale()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Mar 22, 2023 at 11:06:58AM -0300, Arthur Grillo wrote:
> Insert test for the drm_rect_hscale() function, besides the test
> for the usual case it also test for the exceptions.
> 
> Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
> ---
>  drivers/gpu/drm/tests/drm_rect_test.c | 58 +++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tests/drm_rect_test.c b/drivers/gpu/drm/tests/drm_rect_test.c
> index f700984f70a8..7e02393092fa 100644
> --- a/drivers/gpu/drm/tests/drm_rect_test.c
> +++ b/drivers/gpu/drm/tests/drm_rect_test.c
> @@ -9,6 +9,8 @@
>  
>  #include <drm/drm_rect.h>
>  
> +#include <linux/errno.h>
> +
>  static void drm_rect_compare(struct kunit *test, const struct drm_rect *r,
>  			     const struct drm_rect *expected)
>  {
> @@ -225,12 +227,68 @@ static void drm_test_rect_intersect(struct kunit *test)
>  	KUNIT_EXPECT_FALSE_MSG(test, visible, "Interserction should not be a visible rect");
>  }
>  
> +static void drm_test_rect_calc_hscale(struct kunit *test)
> +{
> +	struct drm_rect src, dst;
> +	int scaling_factor;
> +
> +	drm_rect_init(&src, 0, 0, 2, 0);

I think we have a few places in the code that make the assumption
that src uses .16 binary fixed point. Not many, but few.

> +	drm_rect_init(&dst, 0, 0, 1, 0);
> +
> +	scaling_factor =  drm_rect_calc_hscale(&src, &dst, INT_MIN, INT_MAX);

The negative min scale factor is nonsensical.

> +
> +	KUNIT_EXPECT_EQ(test, scaling_factor, 2);
> +}
> +
> +static void drm_test_rect_calc_hscale_out_of_range(struct kunit *test)
> +{
> +	struct drm_rect src, dst;
> +	int scaling_factor;
> +
> +	drm_rect_init(&src, 0, 0, 10, 0);
> +	drm_rect_init(&dst, 0, 0, 1, 0);
> +
> +	scaling_factor =  drm_rect_calc_hscale(&src, &dst, 3, 5);
> +
> +	KUNIT_EXPECT_EQ(test, scaling_factor, -ERANGE);
> +
> +	drm_rect_init(&src, 0, 0, 2, 0);
> +	drm_rect_init(&dst, 0, 0, 1, 0);
> +
> +	scaling_factor =  drm_rect_calc_hscale(&src, &dst, 3, 5);
> +
> +	KUNIT_EXPECT_EQ(test, scaling_factor, -ERANGE);
> +}
> +
> +static void drm_test_rect_calc_hscale_negative_args(struct kunit *test)
> +{
> +	struct drm_rect src, dst;
> +	int scaling_factor;
> +
> +	drm_rect_init(&src, 0, 0, -1, 0);
> +	drm_rect_init(&dst, 0, 0, 1, 0);
> +
> +	scaling_factor = drm_rect_calc_hscale(&src, &dst, INT_MIN, INT_MAX);
> +
> +	KUNIT_EXPECT_EQ(test, scaling_factor, -EINVAL);
> +
> +	drm_rect_init(&src, 0, 0, 1, 0);
> +	drm_rect_init(&dst, 0, 0, -1, 0);
> +
> +	scaling_factor = drm_rect_calc_hscale(&src, &dst, INT_MIN, INT_MAX);
> +
> +	KUNIT_EXPECT_EQ(test, scaling_factor, -EINVAL);
> +}
> +
>  static struct kunit_case drm_rect_tests[] = {
>  	KUNIT_CASE(drm_test_rect_clip_scaled_div_by_zero),
>  	KUNIT_CASE(drm_test_rect_clip_scaled_not_clipped),
>  	KUNIT_CASE(drm_test_rect_clip_scaled_clipped),
>  	KUNIT_CASE(drm_test_rect_clip_scaled_signed_vs_unsigned),
>  	KUNIT_CASE(drm_test_rect_intersect),
> +	KUNIT_CASE(drm_test_rect_calc_hscale),
> +	KUNIT_CASE(drm_test_rect_calc_hscale_out_of_range),
> +	KUNIT_CASE(drm_test_rect_calc_hscale_negative_args),
>  	{ }
>  };
>  
> -- 
> 2.39.2

-- 
Ville Syrjälä
Intel